The invention relates to a method for the analysis of surface measurements and is used in particular for the analysis of scratch tests, wear tests or profilometric measurements.
Scanning the surface with a fine tip of a few micrometers in diameter, usually diamond, and at a constant contact force is a common way to determine the surface profile of a sample by mechanical means. This method is used in profilometers or stylus instruments, as well as in some scratch testers and nanoindenters. As a result, one obtains at least one curve which represents the height profile as a function of the scanning path and which is displayed in a graph on a screen. Corrections are common on the curve, for example correcting a sample slope or ripple. An optical image of the high magnification surface is either not recorded at all or it is displayed independently of the graph with the measuring curve. The measuring path is usually much longer than the image width, which corresponds to a magnification of at least 500×. A method in which exactly the part of the graph in the optical image is displayed, which corresponds exactly to the image position and image width, is not yet known.
Patent EP 2 065 695 B1 describes a method of analyzing a scratch-test scratch using a digital image pickup device with a high magnification lens. The lens is designed to receive only a portion of the scratch. Furthermore, a substrate is used, which is acted upon by means of an indenter with a force. It is characteristic of the method that at the beginning of the method the determination of the initial position of the scratch is made with respect to a reference position. This is followed by the production of the scratch on the substrate by means of the indentator when recording the applied force and at least one further measuring parameter as a function of the displacement of the indenter on the substrate with respect to the reference position. This is followed by the recording of a series of images by means of the recording device. The position of the recorded image of the scratch is always related to the reference position.
This is followed by the synchronization of the recorded images with the curve of the applied force and the other measurement parameters, these then being output subsequently on a screen. The insertion of the force progression by means of the curve is thus displayed after the measurement has been carried out in a diagram with respect to a reference position. No force curve can be shown in the current live image. Another disadvantage is that always a reference position for determining the initial position is needed.
In micro-scratch testing, it is common to scan the surface before and after the test and display the profiles along with the depth of penetration under load. This method has already been described in the patents WO 1994/008219 A1 and U.S. Pat. No. 5,992,224 A and in analogous form in the patent WO 1999/046576 A1 in connection with an apparatus for determining the scratch resistance. In none of these patents, however, the measured profiles are displayed in the image of the surface, in particular not in such a way that even when moving the sample the correct part of the curve is automatically always displayed in the image, which corresponds exactly to the image width.